1. Field of the Invention
The present invention relates to a Liquid Crystal Display (LCD), more particularly to a low temperature poly-silicon (LTPS) LCD.
2. Description of the Related Art
Computer, communication and consumer products have become the main trend of high technology. Portable electronic devices are also the essential products of development. Of course, displays are also included. Today, the displays include: Plasma Display Panel (PDP), Liquid Crystal Display (LCD), Electro-luminescent Display, Light Emitting Diode Display, Vacuum Fluorescent Display, Field Emission Display (FED) and Electro-chromic Display. Compared with these displays, the low temperature poly-silicon LCD, however, has advantages of high resolution, low power consumption, easy manufacturing process, low costs, low operational temperature, etc. It has potential application and can become the main trend for the next generation displays.
Referring to FIG. 1, it is a timing chart of the low temperature polysilicon LCD in the prior art. When the gate terminal driving signals Vg is in low state, the data signal Vdata cannot be applied thereto. When the gate terminal driving signals Vg is in high state at T1, the data signal Vdata can be applied thereto. The pixel voltage Vpixel arises. When the gate terminal driving signals Vg is down to low state at T2, the data signal Vdata also be turned off and the pixel voltage Vpixel charges the capacitor and keeps thereat for turning on the pixel. When the power is disconnected at T3, the gate terminal driving signals Vg and the data signal Vdata suddenly drop to 0V. Because the NMOS thin film transistors have been turned off, the charges stored in the capacitor can not be discharged immediately. Therefore, remaining images will exist on the LCD for tens of seconds to several minutes.
Referring to FIG. 2, an I-V curve of the NMOS thin film transistor of the low temperature poly-silicon LCD panel in prior art is shown. The gate terminal driving signals Vg has a high state Vgh and a low state Vgl. Because the threshold voltage of the NMOS thin film transistors and the voltage of the driving circuit are both higher than 0V, the remaining images exist. Therefore, when the gate terminal driving signals Vg is down to 0V, the NMOS thin film transistors are turned off and the pixel voltage Vpixel cannot be discharged immediately.